Senior Project Electrical Engineering 2005

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Senior Project Electrical Engineering 2005
Wireless Baby Monitor
Nelson Rosario, Farida Siddiqi
Advisors Professor Ekram Hassib
Professor Emad A. Andarawis

• Abstract The principle behind our wireless
  infant monitoring system involves the activation
  of a video camera by the detection of a childs
  cry in the environment. Once the video camera has
  been activated, video and sound are transmitted
  to the parent, through wireless communications,
  in which the parent will receive this data on a
  handheld device. In this project the theory
  behind infant cries is researched and implemented
  in the design of a triggering methodology for
  activating the monitoring system and alerting the
  parents.

Why design a new wireless baby monitor? - A
design which will combine the features offered by
individual wireless baby monitors into one system
and incorporates video and audio transmission
with the detection of sound.
Infant Cry Modes Infants have three modes of
vocal mechanisms -Phonation the vocal cords are
fully vibrating periodically at a frequency
between 250 Hz and 650 Hz. -Dysphonation
turbulence noise is generated at the vocal cords
and is modulated by vocal fold vibrations.
Frequency between 650 Hz-850 Hz -Hyperphonation
when the frequency of the vocal cords shifts to
900 Hz- 1200 Hz. For our purposes we are
interested in this frequency range.
Design of FAN05 Microphone/Camera- captures
analog audio/video signal and sends to
transmitter Transmitter- receives audio/video
signal converts to modulated radio frequency
signal and transmits to receiver Receiver- picks
up modulated radio frequency, converts it to
original audio/video signal Trigger Circuit
Triggers the monitor to turn on and emits an
audio signal to get the response of the
parent. Monitor- device which allows parent to
see child

• Analog Audio Signal Results
• Microphone signal music is playing on the
  computer volume 61, approximately 15 inches from
  computer speaker
• Microphone signal music is playing on the
  computer volume 100,15 inches from computer
  speaker

• The Trigger Circuit
• The trigger circuit is the portion of the
  apparatus that consists of the microphone,
  amplifier, bandpass filter, diode rectifier, low
  pass filter, comparator, and timing circuit. The
  trigger circuit starts with a child's cry that
  will be picked up by the microphone. Then the
  signal will be amplified and sent through a band
  pass filter. If the frequency of the voice is
  between 900 Hz and 1200 Hz then the signal will
  be rectified by the diode then the signal will
  pass through a low pass filter to eliminate the
  high frequency components. The resulting DC
  signal will trigger one of the comparator inputs.
  Then a reference voltage of 0.5V will be
  connected to the second input of the comparator.
  When the rectified signal is lower than 0.5V then
  we have a low output. When the rectified signal
  is higher than 0.5V then we have a high output.
  When the output of the comparator is high this
  will trigger the reset pin at the TLC555 timing
  circuit generating a square wave output. The
  square wave is added to the video and audio
  signals to be transmitted. This square wave is
  used to generate an alarm signal at the receiver.

Video Results for FAN05 video signal when a
hand is approximately 7.5 inches from the
lens video signal when a hand is standing
approximately 21 inches from the camera lens
Pspice-Filter Circuit Design
Results of Pspice for filter design
Results of Constructed Circuit
Not triggering at 800Hz
Triggering at 1100Hz
Triggering at 1200Hz
Output of TLC555 Timing Circuit